The present technology generally relates to tires for vehicles, and more specifically to non-pneumatic tires.
Tires currently used on vehicles are generally pneumatic tires, having a toroidally shaped body made of a flexible elastomer material, such as rubber, with reinforcing materials such as fabric and wire, and being filled with compressed air to form an inflatable cushion. Pneumatic tires generally fit around a standard rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock. With such tires, internal air pressure is necessary to carry the load acting on the tires. Vehicle tires working with internal air pressure function well in practice, however, they do suffer from significant drawbacks. Such drawbacks include complex structural designs as well as safety issues in the event of a puncture during their use on public roads.
Airless, or non-pneumatic, tire designs exist in the prior art. However, several known non-pneumatic tire designs are unsuitable for carrying loads over approximately 450 lbs., as the crown portions of the springs of each become flat and, due to the large deformation, the springs fatigue and break. Additionally, some known non-pneumatic tire designs can only be used on vehicles with low traveling speeds, such as vehicles having a maximum speed of 25 mph to 35 mph. In cases of a larger load or faster speed, the temperature of the vehicle tires can significantly exceed the acceptable temperature limit of 175° F. to 195° F. due to large spring deformations. As a consequence, the rubber material of the tire body can age very quickly, becoming thereby unsuitable for further use. A further disadvantage of some known non-pneumatic tires is the small side stability characteristic for their high profiles. This makes their safe operation in today's high-speed vehicles impossible.
U.S. Pat. No. 1,113,036 to Mitchell describes a pneumatic tire having a series of arched and transversely extending bands or straps of metal, which are each terminally looped around the bead rings of the tire, in order to increase the puncture resistance of the tire. The arched bands extend throughout the cross sectional area of the outer case of the tire, and they are embedded in the outer case of the tire throughout their length. The side edges of the arched bands are rounded and bear against each other.
U.S. Pat. No. 1,471,580 to Walton describes a tire that has a skeleton framework formed of substantially U-shaped wire elements, each of which has its cross head bent into a channel shape. The ends of the wire elements have loops or eyes that receive cables or wires employed in securing the elements together. The skeleton frame is embedded in vulcanized fiber, which provides a channel-shaped recess around the periphery of the skeleton frame to receive a key-stone cushion of hard rubber, which is in the form of a band encircling the skeleton frame.
U.S. Pat. No. 1,610,238 to Benson discloses a tire having a series of spring elements bent in a substantially horse-shoe form, which are molded and embedded in the casing of the tire, and preferably do not protrude therefrom at any point. In the central portion of each spring, adjacent to the tread of the tire, a circular loop or eye is formed, and a rod or heavy wire extends circumferentially of the tread portion of the casing and passes through the loops of all the spring elements. At the ends of the spring elements, adjacent to the rim portion of the casing, the spring elements are formed with eyes through which wires extend that similar to conventional bead rings.
U.S. Pat. No. 6,994,135 to Delfino describes a flexible tire including a flexible load-bearing structure extending circumferentially about an axis of rotation, a tread on the radially outer periphery of the load-bearing structure, and at least one fastening zone, radially to the side of the axis of rotation, for immobilizing the load-bearing structure on a wheel disc. The tire also includes a plurality of support elements extending essentially transversely, a first part of which is arranged at least facing the tread, and another part of which is arranged beyond the tread, the support elements being juxtaposed circumferentially and distributed around the full circumference of the load-bearing structure. The load-bearing structure also comprises an interconnection structure between the support elements, preferably arranged radially between the tread and the support elements. The profile of the tire defines a toric inner cavity of ovoid section.
Commonly assigned U.S. Pat. No. 6,374,887 to Subotics discloses a tire which is of an elastic material, preferably rubber or an elastomer, and is provided with a crown portion and sidewalls adjacent to the crown portion, wherein both sidewalls terminate in beads by which the tire is mounted on a wheel rim in a pre-stressed (biased) state. The internal boundary surface of the crown portion oriented toward the wheel rim is provided with transverse troughs spaced circumferentially at specified distances from one another. Between every two adjoining troughs stiffening ribs are defined, which interconnect the crown portion, the sidewalls, and the beads. The stiffening ribs are supported by arcuately bent leaf springs, the endings of which are resiliently embedded in the beads. The leaf springs are situated along the internal boundary surface of the crown portion at specified intervals, and are positioned to connect the two beads with one another. The beads, in turn, are held in a wheel rim in a pre-stressed state.
Commonly assigned U.S. Pat. No. 7,546,862 discloses non-pneumatic tires having a body made of an elastic material. The body has a crown portion containing the running surface and two sidewalls joined to the crown portion via shoulder portions and ending in beads. Radially placed curved springs are situated so as to be circumferentially-spaced in specified distances from each other and extend from one bead to the other. The tire's beads are secured within the flange of a standard rim by tension as the beads are stretched to get over the flange of the rim during installation of the tire onto the rim. The curved springs are embedded in the tire body at least along the crown portion. The shape of the springs can be semi-elliptical, or can be a compound-curve having S-shaped sidewalls.